Posted by Tim Jackson on April 4, 2009, 11:05 pm
Eeyore wrote:
>
> Alistair Gunn wrote:
>
>> In alt.energy.renewable Eeyore twisted the electrons to say:
>>>> Actually it wouldn't be "them" switching your appliances on/off, your
>>>> appliances would do it automatically based on their own state and the
>>>> condition of the national grid. I haven't found conclusive proof as yet,
>>>> but it seems that fridges with this sort of dynamic demand are now being
>>>> sold in the UK ...
>>> I'd like to know where they get their data from.
>> It monitors the mains frequency ...
>
> The mains frequency is very rock solid. It HAS to be for the gris to work.
You're
> talking crap.
>
> Graham
>
The instantaneous mains frequency isn't rock solid. The control system
keeps the long term *average* mains frequency rock solid so that
synchronous electric clocks stay in time, In the short term the
frequency drifts by anything up to a Hz or so.
The main reason is the time it takes mechanical generators to respond to
changes in overall load.
See, for example,
http://en.wikipedia.org/wiki/Mains_frequency
Tim Jackson
Posted by Eeyore on April 4, 2009, 11:11 pm
Tim Jackson wrote:
> Eeyore wrote:
> > Alistair Gunn wrote:
> >
> >> In alt.energy.renewable Eeyore twisted the electrons to say:
> >>>> Actually it wouldn't be "them" switching your appliances on/off, your
> >>>> appliances would do it automatically based on their own state and the
> >>>> condition of the national grid. I haven't found conclusive proof as yet,
> >>>> but it seems that fridges with this sort of dynamic demand are now being
> >>>> sold in the UK ...
> >>> I'd like to know where they get their data from.
> >> It monitors the mains frequency ...
> >
> > The mains frequency is very rock solid. It HAS to be for the grid to work.
You're
> > talking crap.
> >
> The instantaneous mains frequency isn't rock solid. The control system
> keeps the long term *average* mains frequency rock solid so that
> synchronous electric clocks stay in time, In the short term the
> frequency drifts by anything up to a Hz or so.
Utter nonsense. Except in 3rd world countries maybe.
Graham
Posted by Ken on April 5, 2009, 6:47 am
On Sun, 05 Apr 2009 00:11:34 +0100, Eeyore
> > >> In alt.energy.renewable Eeyore twisted the electrons to say:
> > >>>> Actually it wouldn't be "them" switching your appliances on/off, your
> > >>>> appliances would do it automatically based on their own state and the
> > >>>> condition of the national grid. I haven't found conclusive proof as
yet,
> > >>>> but it seems that fridges with this sort of dynamic demand are now being
> > >>>> sold in the UK ...
> > >>> I'd like to know where they get their data from.
> > >> It monitors the mains frequency ...
> > >
> > > The mains frequency is very rock solid. It HAS to be for the grid to work.
You're
> > > talking crap.
> > >
> > The instantaneous mains frequency isn't rock solid. The control system
> > keeps the long term *average* mains frequency rock solid so that
> > synchronous electric clocks stay in time, In the short term the
> > frequency drifts by anything up to a Hz or so.
>
> Utter nonsense. Except in 3rd world countries maybe.
In Europe.
Posted by Eeyore on April 5, 2009, 10:25 pm
Ken wrote:
> > > >> In alt.energy.renewable Eeyore twisted the electrons to say:
> > > >>>> Actually it wouldn't be "them" switching your appliances on/off, your
> > > >>>> appliances would do it automatically based on their own state and the
> > > >>>> condition of the national grid. I haven't found conclusive proof as
yet,
> > > >>>> but it seems that fridges with this sort of dynamic demand are now
being
> > > >>>> sold in the UK ...
> > > >>> I'd like to know where they get their data from.
> > > >> It monitors the mains frequency ...
> > > >
> > > > The mains frequency is very rock solid. It HAS to be for the grid to
work. You're
> > > > talking crap.
> > > >
> > > The instantaneous mains frequency isn't rock solid. The control system
> > > keeps the long term *average* mains frequency rock solid so that
> > > synchronous electric clocks stay in time, In the short term the
> > > frequency drifts by anything up to a Hz or so.
> >
> > Utter nonsense. Except in 3rd world countries maybe.
> In Europe.
I suggest you look up the regulations. You're talking out of your arse.
" In the continental European UCTE grid, the deviation between network phase
time and UTC
is calculated at 08:00 each day in a control center in Switzerland, and the
target
frequency is then adjusted by up to ±0.02% from 50 Hz as needed, to ensure a
long-term
frequency average of exactly 3600×24×50 cycles per day is maintained.[15] "
http://en.wikipedia.org/wiki/Utility_frequency#Long-term_stability_and_clock_synchronization
+/- 0.02% !
Graham
Posted by Tim Jackson on April 5, 2009, 11:21 pm
Eeyore wrote:
>
> Ken wrote:
>
>>
>>>>>> In alt.energy.renewable Eeyore twisted the electrons to say:
>>>>>>>> Actually it wouldn't be "them" switching your appliances on/off, your
>>>>>>>> appliances would do it automatically based on their own state and the
>>>>>>>> condition of the national grid. I haven't found conclusive proof as
yet,
>>>>>>>> but it seems that fridges with this sort of dynamic demand are now being
>>>>>>>> sold in the UK ...
>>>>>>> I'd like to know where they get their data from.
>>>>>> It monitors the mains frequency ...
>>>>> The mains frequency is very rock solid. It HAS to be for the grid to work.
You're
>>>>> talking crap.
>>>>>
>>>> The instantaneous mains frequency isn't rock solid. The control system
>>>> keeps the long term *average* mains frequency rock solid so that
>>>> synchronous electric clocks stay in time, In the short term the
>>>> frequency drifts by anything up to a Hz or so.
>>> Utter nonsense. Except in 3rd world countries maybe.
>> In Europe.
>
> I suggest you look up the regulations. You're talking out of your arse.
>
> " In the continental European UCTE grid, the deviation between network phase
time and UTC
> is calculated at 08:00 each day in a control center in Switzerland, and the
target
> frequency is then adjusted by up to ±0.02% from 50 Hz as needed, to ensure a
long-term
> frequency average of exactly 3600×24×50 cycles per day is maintained.[15] "
>
http://en.wikipedia.org/wiki/Utility_frequency#Long-term_stability_and_clock_synchronization
>
> +/- 0.02% !
>
> Graham
>
That's the TARGET frequency DAILY adjustment. The ACTUAL frequency
varies on the ten-second time-scale with load changes, the generating
station local control systems adjust the power input to maintain the
daily average close to that target frequency.
Alistair Gunn posted in this thread that the UK statutory requirement is
plus or minus half a Hz, I didn't know that when I posted earlier, I
just knew from observations that it fluctuates over a range of something
approaching 1Hz over minutes under heavy load conditions, eg over the
notorious "tea-break" load spike. Or it did several years ago when I
made those observations.
If you don't believe me go stick a frequency meter on your domestic
supply and see where it's at. IIRC most of the time it was +/- 0.1Hz or
so, with occasional larger excursions.
Tim Jackson
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> Alistair Gunn wrote:
>
>> In alt.energy.renewable Eeyore twisted the electrons to say:
>>>> Actually it wouldn't be "them" switching your appliances on/off, your
>>>> appliances would do it automatically based on their own state and the
>>>> condition of the national grid. I haven't found conclusive proof as yet,
>>>> but it seems that fridges with this sort of dynamic demand are now being
>>>> sold in the UK ...
>>> I'd like to know where they get their data from.
>> It monitors the mains frequency ...
>
> The mains frequency is very rock solid. It HAS to be for the gris to work.